Circuit interrupter



1937. T. BIRKENMAIER ET AL 2,091,802

CIRCUIT INTERRUPTER Filed Sept. 25, 1935 Patented Aug. 31, 1937 UNITEDSTATES PATENT OFFICE Mosley,

Richmond Heights, Mo., assignors to The W. N. Matthews Corporation, St.Louis, Mo., a corporation oi Missouri Application September 23, 1935,Serial No. 41,650

11 Claims.

This invention relates to circuit interrupters, and with regard tocertain more specific features, to an interrupter responsive tothermostatic action.

Among the several objects of the invention may be noted the provision ofan improvement upon the construction shown in the United States Patent2,025,525 of Ralph R. Pittman and Carroll H. Walsh, filed August 6,1934, dated December 24, 1935, for Circuit interrupter; the provision ofapparatus of the class described which may be simply applied by screwinga plug into a socket and pressing a cap with longitudinal movement only;the provision of apparatus of the class described which shall open thecircuit upon overload and which shall not be immediately reclosable; theprovision of a device of the class described in which, if it be reclosedin an overloaded circuit, will promptly interrupt said circuit; and theprovision of apparatus of this class which is more compact in form andsimpler to operate. Other objects will be in part obvious and in partPointed out hereinafter.

The invention accordingly comprises the elements and combinations ofelements, features of construction, and arrangements of parts which willbe exemplified in the structures hereinafter described, and the scope ofthe application of which will be indicated in the following claims.

In the accompanying drawing, in which are illustrated two of variouspossible embodiments of the invention,

Fig. 1 is a side elevation showing one form of the invention;

Fig. 2 is a vertical section taken on line 2-2 of Fig. l, the devicebeing shown in open-circuit position;

Fig. 3 is a view similar to Fig. 2 showing the device in closed-circuitposition;

Fig. 4 is a vertical section taken on line 4-4 of Fig. 3;

Fig. 5 is a cross section taken on line 55 of Fig. 2;

Fig. 6 is a cross section taken on line 6-6 of Fig. 3;

Fig. '1 is a cross section taken on line 1-1 of Fig. 3; and,

Fig. 8 is a fragmentary view similar to the one shown in Fig. 3, butshowing an alternative embodiment of the invention.

Similar reference characters indicate corresponding parts throughout theseveral-views of the drawing.

Referring now more particularly to Fig. 1, there is shown at numeral I acylindric, metallic, current-conducting body having round threads 3 forapplication to the usual electric socket. The body I forms a firstcontact.

Held in the bottom of the body I is 9. diaphragm 5 of di-electricmaterial which holds a central, second contact 1.

Attached to the inside of the body I by means of a force fit is ametallic guide bushing 9 providing an annular recess II for a coilspring I3, the latter reacting from the bottom of said recess II againsta flange I5 of a metallic slide I1. Parts 9 and I1 are both conductors.

The slide I1 slidably bears on the bushing 9 at its lower end and isflanged outwardly at I5 to slidably bear at I 9 on the body I. The bodyI carries a fixed pin 2| which, at its inner end is engaged by a groove23 formed in the enlarged portion III of said slide I1, thus preventingrelative rotation of slide I1 and body I.

The slide I1 carries a bi-metaliic thermostat 25 of inverted U-shape,one leg of which is held to the slide I1 by a fasteher 21, the latterbeing insulated from said slide I1. The fastener 21 ,also holds a third,U-shaped, spring contact 29. The other leg of the thermostat 25 iselectrically connected at 3| with said slide I 1. By pressing the slideI1 downwardly the third contact 29 engages the second contact 1 as shownin Fig. 3.

The upper end of the U-shaped thermostat 25 is free and has fastenedthereto a latch pin 33, notched as shown at 35 to normally engage oneside of an opening 31 in a metallic washer 39 held fast in an insulatingcap 4i, the latter being arranged slidably on the outside of the body I.The cap 4| carries a groove 43 which cooperates with the outside end ofsaid fixed pin 2| to prevent relative rotation between said cap 4| andbody I but to permit reciprocation thereof on the body. A pin 45 in thelower end of the groove 43 prevents the cap M from being entirelyremoved from the body I.

The slide I1 is limited in its upward travel by means of a ring 41forced into the upper end of the body I. The ring 41 carries a flange 49(which, however, may be omitted) and at its lower end effects a flange5| with respect to the inside cylindric form of the body I.

Springs 50 normally force the cap H in a direction to contact the pin 45with pin 2|,

and thus normally to place the lower edge of the washer 39 above thenotch 35 in the latch 33 in the upper position of the latter.

The cap 4I pivotally carries a latch 53 which is pressed by means ofspring 55 to a position to catch either the flange 49 (when used) or theflange i depending upon the elevation of the cap 4! from the bottom ofthe device.

The thermostat 25 has a normal cold position shown by solid lines inFig. 4 and a hot position 5 shown by the dotted lines in that samefigure. The cold position is the one which is effective during normalcurrent flow, and the hot position is the one which clears duringabnormal current flow, the material and cross-section of the thermostatbeing calculated to produce this effect in view of the current flowing.

Starting with the device as shown in Figure 2 which is its open-circuitposition, it maybe screwed into a socket and then the cap ii pushed downto the position shown in Fig. 3. Inasmuch as the latch pin 33 at thisstage has its notch 35 in the solid-line position shown in Figs. 4 and6, the washer 39 will contact the notch and force the thermostat 25downwardly, thus carrying along the slide ll against the reaction ofspring l3. Finally, the latch 53 catches under the flange 5| to hold theparts in the position shown in Fig. 3, wherein the contact 29 is inelectrical engagement with the contact l. Current then flows through thecontacts I and 29, fastener 21, through the thermostat 25, slide l1,bushing 9, body I, and to the line. Under normal conditions of currentflow, the solid-line position of thelatch pin 33, as shown in Fig. 4,will be maintained. I

Upon overload, the thermostat 25, having been chosen for proper value ofresistance to bring about the effect, deflects to the dotted-lineposition shown in Figure 4. This immediately clears the notch 35 fromthe washer 39 (dotted lines of Fig. 4, and Fig. 5) and the slide I]under the influence of the spring l3 jumps from the position shown inFigs. 3 and 4 to the position shown in Fig. 2. This causes the upper endH of the 40 slide I! to contact the sloping face 56 of the latch 53,thus moving the latch from its caught position on the flange 5|. Thisreleases the cap 8| which, under the influence of springs 50, move fromthe position shown in Fig. 3, to that shown in Fig. 2.

If the user then attempts immediately to push back the cap 4|, toreclose the circuit, he will not meet with success because thethermostat 25 takes some time to cool and before doing so,

maintains its deflected, dottedline position. Thus the pin 33 freelypames through the hole 31 (Fig. 5). The time taken for cooling isusually enough to clear the line of trouble and if it is not, aresetting will again result in deflection of the thermostat and asubsequentrelease with consequent re-opening of the circuit.

In Fig. 8 is a modified form of the invention in which like numeralsdesignate like parts. In this form, a shunt resistance 51 is held by thefas- 30 tener 21 and is placed in electrical contact with the slide I!by means of a second fastener 59. The purpose of this resistance is tofunction as a calibrating means for the thermostat 25. Thus, with onedesign of structure such as shown in 5 Figs. 1 to 7, various overloadconditions may be met by varying the resistance 51. At the time ofmanufacture, the proper valueof resistance 57 is determined, the samedepending upon the conditions of operation of the fuse.

70 The latch 53 is provided with a finger El with which cooperates astem 63 of a button 65. The stem and the button are slidable in the cap4! and the stem 63 is held prisoner by a pin 61 in the cap whichintersects a notch 69 in said pin 63.

75 By manually pressing the button 65 the latch 53 may be removed fromthe flange 5!, thus to cause the slide i! to be forced to open-circuitposition. The strength of spring 55 is such that the release can beeffected without requiring a force at the button 65 great enough toprevent the spring l3 from expanding.

In view of the above, it will be seen that the several objects of theinvention are achieved, and other advantageous results attained.

As many changes could be made in carrying out the above constructionswithout departing from the scope of the invention, it is intended thatall matter contained in .the above description or shown in theaccompanying drawing shall be interpreted as illustrative and not in alimiting sense.

We claim:

1. A circuit interrupter comprising a contact body member, a secondcontact attached thereto but electrically separated therefrom, a sliderin the body member normally biased away from said second contact, alatch-holding means on said body, a reciprocating cap on said body, alatch in said cap cooperable with said latch-holding means, a deflectingthermostat mounted on said slider and electrically connected theretoexclusively at one end, a third contact electrically connected to thethermostat at its other end movable into and out of engagement with saidsecond contact upon reciprocation of the slider, a latch controlled bydeflection of said thermostat, means on the cap cooperating with saidlatch in the cold position of the thermostat to permit forcing of theslider to a position where the third and second contacts electricallyengage, said latch on the head being held on said latch-holding means onthe body, said slider being adapted to subsequently release said latchon the head from its latch-holding means upon deflection of thethermostat.

2. In a circuit interrupter, a cylindric body, forming an electricalcontact, a second contact fastened to said body but electricallyseparated therefrom, a; third contact, a hollow slider in said bodynormally biased away from said second contact, a U-shaped thermostatsupported in the hollow slider and open downwardly, one leg of which iselectrically connected to the slider and the other of which is insulatedtherefrom, said last-named leg having electrically connected theretosaid third contact, a reciprocating head on said body, a latch movableby deflection of said thermostat, latch-engaging means on said headadapted to engage the latch in the cold position of the thermostat andto disengage therefrom in the hot position of said thermostat, and asecond latching means on said head adapted to hold the same against thebias of said slider and to be pushed toward said second contact whilethe thermostat is cold, means for releasing the said last-named latch bysaid slider when said thermostat deflects to release the first-namedlatch, and biasing means normally pressing the cap away from saidsecond-named contact.

3. A circuit interrupter comprising a cylindric conducting body threadedto thread into a threaded socket, a second, central insulated contactassociated with said body, a conducting slider in said body, a springcontact mounted on and beneath said slider and springingly cooperablewith said second contact upon reciprocation of the slider, a U-shapedthermostat within the slider positioned withits open side downwardly,one leg of said thermostat being insulated from the slider and attachedto said spring contact, the

other leg being electrically connected with the slider, a reciprocatinghead on the body, latching means between said thermostat and said headadapted to effect movement of the slider from said head when thethermostat is cold and another latch on the head adapted to hold thesame against the bias of the slider in the cold position of thethermostat.

4. A circuit interrupter comprising a cylindric conducting body threadedto enter a threaded socket, a central insulated contact associated withsaid body, a conducting slider in said body, a spring contact mounted onsaid slider and cooperable with said second contact upon reciprocationof the slider, a U-shaped thermostat within the slider positioned withits open side downwardly, one leg of said thermostat being insulatedfrom the slider and attached to said spring contact, the other leg beingelectrically connected with the slider, a reciprocating head on thebody,

latching means between said thermostat and said head adapted to effectmovement of the slider from said head through the thermostat when thelatter is cold, and another latch on the head adapted to hold the samedown against the bias of the slider in the cold position of thethermostat, said first-named latching means between the thermostat andthe head in the hot position of the thermostat releasing to permitbiasing movement of the slider, said slider and said secondnamed latchmeans being cooperable to release the head after said movement of theslider.

5. A circuit interrupter comprising a cylindric conducting body threadedto enter a threaded socket, a central insulated contact associated withsaid body, a conducting slider in said body, a spring contact mounted onsaid slider and cooperable with said second contact upon reciprocationof the slider, a U-shaped thermostat within the slider positioned withits open side downwardly, one leg of said thermostat being insulatedfrom the slider and attached to said spring contact, the other leg beingelectrically connected with the slider, a reciprocating head on thebody, latching means between said thermostat and said head adapted toeffect movement of the slider from said head through the thermostat whenthe latter is cold, and another latch on the head adapted to hold thesame down against the bias of the slider in the cold position of thethermostat, said first-named latching means between the thermostat andthe head in the hot position of the thermostat releasing to permitbiasing movement of the slider, said slider and said secondnamed latchmeans being cooperable to release the head after said movement of theslider, and means biasing said head in the direction of the bias of saidslider.

6. A circuit interrupter comprising a body forming one contact, a secondcontact insulated therefrom but mounted thereon, a biased slidertherein, a third contact on said slider, a deflecting thermostat mountedon said slider, a reciprocating head on said body, latch means betweenthe thermostat and the head, and means for holding the head against thebias of the slider upon movement of the same when the thermostaticallycontrolled latch is in cold position, said latch opening to release theslider to assume its bias in the hot 70 position of the thermostat, saidslider cooperating with the means holding the head to release the same.

'I. A circuit interrupter comprising a body forming one contact, asecond contact insulated 75 therefrom but mounted thereon, a biasedslider therein, a third contact on said slider, a deflecting thermostatmounted on said slider, a reciprocating head on said body biased in adirection away from said slider, a first latch means between thethermostat and the head, a second latch means between the head and bodyfor holding the head against the bias of the slider upon movement 01'the head against bias of the slider when the thermostatically controlledlatch is in cold position, said flrst'latch opening to release theslider to assume its bias in the hot position of the thermostat, saidslider cooperating with the second. latch means to release the head.

8. A circuit interrupter comprising axially movable contact members foropening and closing of circuit, a thermostat carried by one of saidmembers, biasing means opposing the engagement of said contact members,a movable cap for urging said contact members to closed circuitposition, a latch normally holding the cap against said biasing means,said thermostat cooperating with the cap for normally maintaining theinterrupter in closed circuit position when said latch normally holdsthe cap against the action of said biasing means, said thermostatcarrying current and adapted upon overload to heat itself and todisengage from said cap for permitting the switch to assume an opencircuit position.

9. A circuit interrupter comprising axially movable contact members foropening and closing of circuit, a thermostat carried by one of saidmembers, biasing means opposing the engagement of said contact members,a movable cap for urging said contact members to closed circuitposition, a latch normally holding the cap against said biasing means,said thermostat cooperating with the cap for normally maintaining theinterrupter in closed circuit position when said latch normally holdsthe cap against the action of said biasing means, said thermostatcarrying current and adapted upon overload to heat itself and todisengage from said cap for permitting the switch to assume an opencircuit position, and separate biasing means for biasing the cap to aposition wherein the thermostat may again cooperate therewith when theswitch is open, said latch being adapted to be opened when the switchassumes open-circuit position so that said last-named biasing means mayoperate on the cap.

10. A circuit interrupter comprising axially movable contact members foropening and closing of circuit, a thermostat carried by one of saidmembers, biasing means opposing the engagement of said contact members,a movable cap for urging said contact members to closed circuitposition, a latch normally holding the cap against said biasing means,said thermostat cooperating with the cap for normally maintaining theinterrupter in closed circuit position when said latch normally holdsthe cap against the action of said biasing means, said thermostatcarrying current and adapted upon overload to heat itself and todisengage from said cap for permitting the switch to assume an opencircuit position, a separate biasing means for biasing the cap to aposition wherein the thermostat "may again cooperate therewith when theswitch is open, said latch being adapted to be opened when the switchassumes open-circuit position so that said lastnamed biasing means mayoperate on the cap, cooperation between the thermostat and cap forclosing the switch being adapted to take place thereatter only when thethermostat is in a cold position, said cap and its latch being freelyreciprocable and unadapted to force or hold the switch in closed-circuitposition.

11. A circuit interrupter comprising axially movable contact means foropening and closing a circuit, a thermostat carried by one of saidmembers and forming a driving link whereby said members may be driven toclosed-circuit position, biasing means opposing the engagement of saidcontact members, a movable cap for urging said contact members toclosed-circuit position, a latch normally holding the cap against saidbiasing means when the contacts are closed, said thermostat in its coldP sition cooperating with the cap for normally maintaining theinterrupter in closed-circuit position while said latch normally holds,and said thermostat carrying current for heating itself whereby uponoverload it will disengage from said cap for permitting the switch toassume an open-circuit position, the separation of the contact memberseflecting opening of said latch, and means whereby said cap is thendriven to a position to be engaged by said thermostat'for reclosing saidcontact members by movement of said cap it and when said thermostatassumes a cold position.

THEODORE BIRKENMAIER. CARL E. MOSLEY.

